Researchers at Queens University-Belfast have subjected crabs to small electrical shocks to determine whether live crustaceans such a crabs, prawns and lobsters feel pain. They examined the reactions of crabs to small electrical shocks, and their behavior after being shocked, to reach their conclusion. Professor Bob Elwood’s earlier research revealed that crabs feel pain, but this latest study offers additional evidence of this conclusion.
Elwood said in a statement that he and his colleagues designed the experiment to differentiate between pain and a reflex phenomenon called nociception. According to Elwood, the job of pain is to help future evasion of the pain source, whereas nociception allows a reflex response that supplies immediate protection from the pain source, but no changes to long-term behavior. Elwood posited that whether or not crustaceans feel pain is still a widely debated topic.
Elwood’s findings reveal that crabs are willing to trade a dark shelter to avoid future electric shock. This a big deal for researchers, because crabs love dark shelters where they can hide from predators. Researchers concluded that crabs feel pain, because they left a valued hiding spot in order to avoid a small electric shock.
Researchers placed ninety crabs in a tank with two dark shelters one at a time. After the crabs moved into one of the shelters, researchers subjected some of them to an electric shock. After a short period of rest time, each crab was placed in the tank again. Most of the crabs returned to the shelter, but those that had been shocked the first time were shocked again. When researchers introduced them to the tank for the third time, however, most of the shocked crabs now went to the second shelter, where they had not been shocked the first two times.
Elwood said that the crabs learned to avoid the shelter where they received the shock. In other words, they were okay with giving up their hideaway in order to avoid the source of their pain.
The research team said they hope that their findings lead to investigations into how crabs and other crustaceans used in food industries are handled. According to Elwood, crustaceans are handled roughly as the presumption is that they cannot experience pain. The findings of this study suggest otherwise.
While it is impossible to prove without question that an animal experiences pain, criteria that suggest what would be expected if pain were to be experienced have been tested and the findings are consistent with the idea of pain, according to researchers.
The study was recently published in the Journal of Experimental Biology.